1. Field of the Invention
This invention relates to an image forming apparatus, such as an electrophotographic printer, for forming an image on an image bearing member and, more paticularly, to an image forming apparatus having a disordering device for disordering a developing agent remaining on the image bearing member.
2. Description of the Related Art
Generally, in a conventional image forming apparatus, a latent image is first formed on an image bearing member which has had its entire surface charged by a charging device. A developing device then develops the latent image using a developing agent (toner) to make the latent image visible. Subsequently, the developed image is transferred onto a paper sheet by a transferring device. Most of the toner of the developed image on the image bearing member is transferred onto the paper sheet by the transferring device. However, some of the toner of the developed image remains on the image bearing member after transfer of the developed image by the transferring device. Thus, the residual toner particles on the image bearing member are removed from the image bearing member by a cleaning device.
Recently, in the image forming apparatus, it has been demanded by buyers to reduce the size of the apparatus to a compact type. For example, U.S. Pat. No. 4,727,395 discloses an image forming apparatus which simultaneously carries out the developing and cleaning processes. The image forming cycle of the apparatus is performed with one rotation of its image bearing member. Thus, this image forming apparatus is reduced in size by using an image bearing member having a reduced diameter and a device which serves as a developing device and a cleaning device.
However, in the image forming process described in U.S. Pat. No. 4,727,395, the residual toner image still remains in the next image forming process, for example, a charging process and a latent image forming process (an exposure process). Thus, the charging process and the latent image forming process in the next image forming cycle have to be carried out on the residual toner image remaining on the image bearing member. Therefore, a resulting image formed in the next cycle is deteriorated by the residual toner image remaining on the image bearing member.
In order to solve the above problem, U.S. Pat. No. 4,769,676 discloses an image forming apparatus having a disordering device for disordering the residual toner image remaining on the image bearing member after the transfer of the developed image and before the next image forming operation. The disordering device includes a conductive member in sliding contact with the image bearing member. The conductive member has a bias voltage applied to it. Therefore, by means of a sliding contact between the conductive member and the image bearing member, the residual toner is temporarily attracted to the conductive member and is then deposited over other parts of the surface of the image bearing member. Thereby, the disordering of the residual toner is effected and the residual toner image is made non-patterned.
However, in the image forming apparatus, the body of the apparatus vibrates in certain operations, for example, the operation for removing a jammed paper sheet from the apparatus, the operation for starting the rotation of the image bearing member and so on. By the vibration of the apparatus, the toner particles attracted on the disordering device may be lumped and removed form the disordering device. Thus, the conventional image forming apparatus described in U.S. Pat. No. 4,769,676, charging randomness and exposure randomness may be caused by any deposits of toner particles removed from the disordering device. Therefore, a resulting image formed on the image bearing member in the next image forming cycle is deteriorated.